Proliferation And Differentiation Of Neural Stem Cells In Rat Brain During Experimental Streptococcus Pneumoniae Meningitis

Ojective To investigate the proliferation and differentiation of endogenous neural stem cells in rat brain during experimental streptococcus pneumoniae meningitis.Methods Three weeks old rats were used to construct the models of Streptococcus pneumoniae meningitis,the control group via saline injection and the sham-operation group.The expressions of Bromodeoxyuridine(Brdu) in the subventricular zone and hippocampus of the rats were dynamically detected by immunohistochemical method in 24h,5th day,14th day,21stday after injection respectively.Bromodeoxyuridine(Brdu) labeling method was used to identify the proliferation of endogenous neural stem cells. GFAP as astrocyte marker was used to identify the astrocyte.BrdU/GFAP double-labeling method was used to identify the differentiation of endogenous neural stem cells in the subventricular zone and hippocampus.Results1. The proliferation of neural stem cells in the subventricular zone and hippocampus(1)The expression of Brdu positive cells in the subventricular zoneBrdu positive cells were observed in the subventricular zone of the models of Streptococcus pneumoniae meningitis,the control group and the sham-operation group after 24h,5th day,14th day,21st day of inoculation.Brdu positive cells of the subventricular zone in Streptococcus pneumoniae meningitis rats were increased at 24h post-infection,reach a peak at 5thday,then decrease, the same to the normal at 21st day(P<0.05). Compared with the control and the sham-operation group,the number of Brdu positive cells were increased in 24h,5th day,14th day in Streptococcus pneumoniae meningitis rats(P<0.05),but the same to each other at 21st day in Streptococcus pneumoniae meningitis rats and the control group(P>0.05)while different between in Streptococcus pneumoniae meningitis rats and the sham-operation group(P<0.05).The number of Brdu positive cells of the control group was greater than that of the sham-operation group at 24h and 5th day(P< 0.05),but the same to each other at 14thday and 21st day(P>0.05).The number of Brdu positive cells at 24h was greater than other times during the control group and the sham-operation group(P<0.05).(2)The expression of Brdu positive cells in hippocampusBrdu positive cells were observed in hippocampus of the models of Streptococcus pneumoniae meningitis,the control group and the sham-operation group after 24h,5th day,14th day,21st day of inoculation. In the models of Streptococcus pneumoniae meningitis,the number of Brdu-labeled cells at 24h after infection was no change compared to 5th day and 14thday level(P>0.05),but was greater than 21st day level(P< 0.05).Compared with the control and the sham-operation group,Brdu positive cells in Streptococcus pneumoniae meningitis rats were increased at 24h post-infection, reach a peak at 5th day,then decrease,but still was greater than normal(P<0.05).There was no change compared to the control group and the sham-operation group(P>0.05). In control, the number of Brdu-labeled cells at 24h fter inoculation were increased,but the same as that 5th day and 14th day (P>0.05),while both 24h and 5th day levels were higher than 21stday level(P<0.05). The number of Brdu-labeled cells of all of the times in the sham-operation group was the same as each other(P>0.05).2.Neural stem cells differentiate into astrocytes in the subventricular zone and in the hippocampus(1)The expression of Brdu/GFAP double positive cells in in the subventricular zoneBrdu/GFAP double positive cells were observed in the subventricular zone of the models of Streptococcus pneumoniae meningitis after24h,5thday,14th day,21st day of inoculation, approximately 10% of newborn cells differentiated into astrocytes as indicated by GFAP labeling, the number of Brdu/GFAP double positive cells of all of the times in Streptococcus pneumoniae meningitis rats was the same as each other(P>0.05). Approximately 3% of newborn cells differentiated into astrocytes as indicated by GFAP labeling in the control group and the sham-operation group at 24h day and 5th day,but there were no Brdu/GFAP double positive cells at 14th day and 21st day, There was significant difference among all of the times in the control group and the sham-operation group(P<0.05). Compared with the control and the sham-operation group, Brdu/GFAP double positive cells of the subventricular zone in Streptococcus pneumoniae meningitis rats were increased(P<0.05),while there was no change compared to the control group and the sham-operation group(P> 0.05).(2)The expression of Brdu/GFAP double positive cells in hippocampusBrdu/GFAP double positive cells were observed in hippocampus of the models of Streptococcus pneumoniae meningitis after 24h and 21st day of inoculation, approximately 3% and 15% of newborn cells differentiated into astrocytes as indicated by GFAP labeling at 24h and 21st day, there was significant difference among all of the times in Streptococcus pneumoniae meningitis rats(P<0.05). Compared with the other groups, Brdu/GFAP double positive cells of hippocampus in Streptococcus pneumoniae meningitis rats at 24h and 21st day were different (P< 0.05). There were no Brdu/GFAP double positive cells in others.Conclusions1.The proliferation of neural stem cells in the early stage during Streptococcus pneumoniae meningitis are obviously activated at 24h post-infection, reach a peak at 5th day,then decrease,that show the self-protection of organism and this protection is not enough.2. Neural stem cells partially differentiated into astrocyte during Streptococcus pneumoniae meningitis in the subventricular zone and hippocampus,but the differentiation is insufficient to meet the needs of the body to repair damage.